Mastication analysis can provide an objective basis for studying and diagnosing jaw musculoskeletal disorders. Therefore, the use and development of devices for quantitatively measuring and analyzing jaw movement have become very popular in the consulting room. This paper proposes a simple to be used jaw tracking prototype by using the new miniaturized wireless Inertial Measurement Unit (IMU) named WB-4. The WB-4 IMU primarily contains a mother board, a Bluetooth module and a Li-Polymer battery. The mother board is provided with a microcontroller and 9-axis inertial sensors (miniaturized MEMS accelerometer, gyroscope and magnetometer) to measure the jaw motion. The data transmission between WB-4 and PC is based on the Bluetooth module to realize the wireless communication. The IMU's extremely reduced weight and size allows it to be easily attached to mandible during normal mastication tests without physical restriction to the subjects. Three pilot experiments for mastication analysis of chewing gum were elaborated. A group of 9 healthy subjects kindly participated in the experiment. The preliminary results show that WB-4 IMU can efficiently evaluate the jaw movement and mastication pattern of different subjects, which could provide quantitative information to the doctors for the diagnosing and clinical treatment of different jaw diseases.